Stottlemeyer is in his office nervously checking the time with Disher. They realize Monk is front out and wonder how he'll take it. Monk and Natalie come in and Stottlemeyer has him take a seat. He then informs his friend that the review board had a private meeting to review Monk's case. They no longer want to use him as a private consultant any more. Monk angrily storms out and Natalie complains about Stottlemeyer's activities. Stottlemeyer runs after them and gives Monk his badge: he's been reinstated as a police detective.
Later, Monk is preparing for his first day on the job and makes sure that his bullets are clean. Natalie sends him on his way but as Monk goes, he says he'll miss her. Natalie assures him that they'll get together and talk and be friends. She tells Adrian that she has an interview with concert promoter Jim Paxton, who is looking for an assistant. Monk assures her that Paxton couldn't do better and Natalie hugs him.
Monk arrives at the station and settles in for the staff meeting and Stottlemeyer announces Monk's return. Everyone applauds and Monk briefly gets up and tries to give a speech. Stottlemeyer cuts him off and then informs them that a witness has provided a description on the Pickaxe Killer. Monk is busy sorting the papers before passing them on, and Stottlemeyer finally gets him to pass them on. As Stottlemeyer assigns his detectives, Monk interrupts him. Afterward, Stottlemeyer has Monk's old desk brought up from storage. Monk hangs up his photo of Trudy and settles in, but Stottlemeyer informs him that he promised the review board he would keep him on desk duty for a few days, and then move him over to another squad. He explains that it's protocol and he can't hold Monk's hands anymore. Monk agrees and Stottlemeyer has Sgt. DiMarco come in to set up Monk's computer and hook him into the hotline. DiMarco is a big fan and asks for one of Monk's wipes as a souvenir. Monk is clearly uncomfortable with the computer.
Later, Monk spends his time stacking pencils and incessantly polishing his badge. A signal goes off and Monk is unable to figure out what it is. He finally manages to get the call and put his headset on. The caller says he knows who the Pickaxe Killer is. Monk tries to log the call on the computer and keeps putting the caller on hold. DiMarco comes in and tells Monk that a window washer spotted the Pickaxe Killer and they've made an arrest. Monk tries to put a good face on it but is clearly upset.
Stottlemeyer calls a press conference to announce that Richard Mathis has been arrested and the Pickaxe Killer is in custody. Monk is at a bar with other cops and are watching the conference. Stottlemeyer introduces Manuel Alvarez, the window washer who noticed Mathis with a pickaxe in his car. He'll get a $500,000 reward and the cops discuss whether he'll retire. Monk insists he would retire and inform the other cops that he'll be riding with Louie Doyle the next week. When one of his fellow officers asks about Natalie, Monk insists she's probably miserable.
Natalie drops off papers with her new boss, who tells her she'll be coming to dinner with him to meet Coldplay.
The next week, Monk and Doyle meet with Edith Carriani to investigate Monk's new case. She says that Mr. Barton tried to kill her in her bed by smothering her. Mr. Barton is inside and Edith claims he's going berserk. Monk goes in the front while Doyle covers the back. Inside, Monk draws his gun and tries to break the door down. He finally realizes that it's unlocked and goes inside. The only thing inside is a cat, and Edith runs in to explain that Mr. Barton is a cat. As Monk goes to the window to call Doyle, he realizes that the Burkman Building where the window washer was working is nearby.
Monk goes to the firing range to clean up shells and then talks to his fellow officers about Alvarez. He notes that Alvarez said he was in the Burkman Building at 2:30 looking west, but the sun would have been in his eyes. There's no way that Alvarez could have read Mathis' license plate. The other officers insist that it's a solid case and suggest that Monk is jealous. They order him to let it go/
Later, Alvarez meets with DiMarco in a deserted parking garage. He gives DiMarco a duffel bag as they agreed, but then shoots DiMarco, takes the bag back, and runs away.
Monk goes to the crime scene of DiMarco's death. His officers figure he was mugged but Monk notices a coupon for dog food in DiMarco's hand and realize it's the of a dollar. Monk concludes that someone was paying DiMarco off and gave him phony money to distract him. No one believes him and Weaver warns Monk that he might be right, but he shouldn't say anything until he's 110% sure. Weaver explains that DiMarco was family, and they protect their own. Monk admits that he's not 110% sure.
That night, Edith calls Monk and Doyle again. This time she says it's Mr. Lawrence, who lives upstairs and has gone crazy. Monk thinks it's another cat, but he discovers that Mr. Lawrence is real when he breaks a window and starts screaming.
The next day, Monk calls Natalie to see how she's doing. Things are awkward when they don't have much to say, and Natalie tells Monk to take care of himself before hanging up.
Stottlemeyer and Disher go to DiMarco's wake where his co-workers are gathered. They realize Monk is then when they discover that the fruit salad has been sorted. They find him in the bathroom making sure DiMarco didn't have a dog. Stottlemeyer says that so far, DiMarco has checked out clean, but they'll continue to do what they can. Monk finds a passport application to the Cayman Islands. Stottlemeyer takes him out and Monk talks to DiMarco's wife. He confirms that DiMarco was planning a trip the Cayman Island and had bought tickets a week ago. Doyle and Weaver angrily pull him away and Stottlemeyer quickly gets Monk out.
Monk goes to see Dr. Bell, who insists that Monk has earned his reinstatement. He asks if Monk is happy and Monk finally admits that he can't choose his own cases and nobody wants to work with him. Dr. Bell understands and starts to tell a story from his childhood, but Monk cuts him off. He admits that he was happy before and Dr. Bell suggests that he quit. However, Monk insists that he can't quit.
That night, Monk sits at his desk and polishes his badge... alone. The janitor, Sam, comes in and has a box filled with DiMarco's personal effects from his locker. Monk goes through it and finds a ticket book with numbers on it. He makes out the numbers and realizes it's the license plate of Mathis' car.
The next day, Monk goes to see Alvarez, who says he's running later and invites Monk along on his rising platform. Alvarez explains he gave two weeks' notice and then asks what Monk wants. Monk tells Alvarez that he's under arrest for murder. He's confirmed that Alvarez and DiMarco were on the same softball team. When Alvarez realizes that Monk's partner is late and doesn't know about Monk's theory, the window washer knocks him out.
Doyle and Weaver are in a street and Weaver wonders if Doyle was supposed to meet with Monk. Doyle says he isn't interested in Monk's crackpot theories.
Monk wakes up and discovers that Alvarez has taken his gun and is taking the platform up. Monk manages to get to his feet despite his fear of heights. He explains that DiMarco found Mathis' car, but wanted the money. Since he worked for the police, he couldn't collect the reward. He approaches Alvarez, told him who the killer was, and then Alvarez came up with a story to collect the money. Alvarez got greedy and killed DiMarco and kept the entire reward.
Alvarez admits that he's right and then prepares to set up an accident to dispose of Monk. He puts on a harness and then starts shaking the washer platform back and forth. When that doesn't work, Alvarez raises one end and Monk starts to slide down. He manages to grab the platform control and levels out the platform, and then raises his end up. He jabs Alvarez in the leg with his badge before the man can use Monk's gun, and then knocks him off the platform. Weaver and Doyle finally arrive as Monk lowers the platform and explains what happened. Weaver congratulates him... and Monk tells him that he's quitting.
Monk turns in his badge and gun to Stottlemeyer and admits he's glad it didn't work out. They wonder what he's going to do and tell him to leave via the west entrance. When he wonders what is going on, they say it's a surprise. Monk finally goes out and finds Natalie waiting for him. She informs him that Paxton doesn't need her, and Monk does. They embrace and Monk tells her she's getting a pay cut. As they leave, Monk wonders what the surprise is.